Pascal Newsletter #10
The full source code examples of this issue are available for download.
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Pascal Newsletter #10 - 12-NOV-2000 INDEX 1. A FEW WORDS FROM THE EDITOR 2. MYSQL - WHAT IS MYSQL? - MYSQL LICENSE - DELPHI AND MYSQL - ODBC - LIBMYSQL.DLL - WINZEOS 3. "POST-IT." SIZABLE WINDOWS WITHOUT BORDER OR TITLE - WHY A BORDERLESS AND TITLELESS FORM? - LET'S GET STARTED - MANAGING A FORM WITHOUT BORDERS OR TITLE BAR - AN INVISIBLE MAIN FORM - IT'S NOT A BUG, IT'S A FEATURE - POP-UP MENU 4. LINKS ________________________________________________________________________ 1. A FEW WORDS FROM THE EDITOR Those of you who follow the Developers Newsletter probably have read that -due to work reasons- that newsletter will go monthly. Nevertheless, I'll strive to keep releasing the Pascal Newsletter more or less twice a month as I've been doing so far, though I would really appreciate some help. You can help keep this newsletter going by contributing articles about Delphi programming. You will retain the copyright of all the material you submit to us, but you should grant us a permanent non-revocable royalty-free permission to translate and publish your article (in its original form and translated) as long as we do it in full (including your copyright notice and author information you submit to us for the purpose of being published, like email address, web site, educational institution, etc.), without modifications and free of charge. The newsletters are published by email and at our web site, and each issue is licensed to be copied and reproduced by anyone as long as it is done in full (including copyright notices and authors' information), without modifications and free of charge. If you don't agree to these terms, we can talk about publishing your articles in our web site (not in a newsletter) under your own licensing terms. TAKE THIS OPPORTUNITY TO STAND OUT FROM YOUR COLLEAGUES AND TO ADD A PUBLISHED ARTICLE TO YOUR CURRICULUM VITAE. WE GIVE CERTIFICATES. By the way, in this issue I'm glad to present the first contributed article, which has also been published in our web site: * "Post-it". Sizable windows without border or title http://www.latiumsoftware.com/en/articles/00002.php Changing subjects, there are a couple of new Delphi tips in our web site: * How to close another application? http://www.latiumsoftware.com/en/delphi/00034.php * How to start an application as an icon in the system tray? (With full source code) http://www.latiumsoftware.com/en/delphi/00035.php Regards, Ernesto De Spirito eds2004 @ latiumsoftware.com ________________________________________________________________________ JfControls Library. Multi-language. Multi-appearance. Skins. Privileges. More than 40 integrated and customizable components. Impressive GUI. Centralized resources administration. Multiple programming problems solved. For Delphi 3-7 and C++ Builder 3-6. http://www.jfactivesoft.com/ ________________________________________________________________________ 2. MYSQL WHAT IS MYSQL? ============== MySQL is a reliable, fast, compact, powerful and multi-platform multi- threaded open-source database server. In my opinion it is one of the best products of the Open Source Community and its major weakness is that it doesn't support subqueries (although work is in progress to add this necessary feature). You can find more information and download it from the official web site: http://www.mysql.com MYSQL LICENSE ============= First of all, I would like to thank Antti Halonen <antti@mysql.com> for very kindly answering a long email regarding licensing issues. MySQL is licensed under the terms of the GNU General Public License. It is free for internal use and for ISPs. For example it is free if you use it for software development or for companies that may use it as a database server, and it is also free if you develop a tailor-made application for a client (it is still considered internal use for both parties). The problem arises when you plan to distribute commercial applications that need MySQL to run (embedded use). Under the terms of the GPL, these applications should also be distributed as GPL. If you don't want to distribute them as GPL, you can purchase a commercial license for each application and server machine running MySQL. For example, if you sell 100 licenses of an application "A" and 50 licenses of an application "B" to the same client, to be used in a network where your applications will use 10 MySQL servers running in the same machine, then you should buy only just two licenses to be able to sell your applications to this customer because there is only one server machine (no matter how many MySQL servers it runs) and two applications (no matter how many licenses of each one you sell), so there are only two "application-server" combinations (and therefore only two licenses needed): Application "A" - Server 1 Application "B" - Server 1 A single license costs $200 (USD), and you can buy many licenses before actually using them to take advantage of important discount prices. You can distribute a non GPL application that uses MySQL without paying a license if the use of MySQL is not required (i.e. if the application can alternatively do the same stuff using another database system, server, driver or whatever). DELPHI AND MYSQL ================ Basically, there are two ways of accessing a MySQL database from a Delphi application: using an ODBC driver or the libmysql.dll library. ODBC ---- In the MySQL web site you can find the MySQL ODBC driver for Windows: http://www.mysql.com/downloads/api-myodbc.html After installing this driver you can use the BDE Data Access components or the ADO components to access tables or to perform queries on a MySQL database. To use ODBC, first you should create a DSN using the ODBC Data Sources applet of the Control Panel. For example, I created a DSN named MySQL_Test and configured it to log in as 'root' in the MySQL server located at 'localhost' (you can connect to a remote server using its IP address or its domain name) and open the 'mysql' database. In a Delphi program you would have to use a TDatabase component if you don't want the BDE to show the standard login prompt. You have to set minimally the following properties: AliasName = 'MySQL_Test' DatabaseName = 'MySQL_Test' LoginPrompt = False In a TTable or TQuery component you have to set the DatabaseName property to 'MySQL_Test' and that would be it. The advantage of using ODBC is that you can use the standard Borland Datasets, and the disadvantage is that you have to go thru two layers to get to the MySQL server (the BDE and the ODBC driver), although it must be said that even with ODBC, MySQL is still faster than other database servers. LIBMYSQL.DLL ------------ You can also access a MySQL server using the libmysql.dll library. This file doesn't come with the standard MySQL installation, but you can download it from: http://www.fichtner.net/delphi/mysql.delphi.phtml You should also download the mysql.pas file which is a Delphi a unit that contains the type declarations for using this library. You need to include this unit in the uses clause of any unit from which you want to call the functions contained in the library. The following example opens a connection to MySql server, opens a database, performs a query and stores the result in a StringGrid, and finally closes the connection. uses ..., mysql; procedure TForm1.Button1Click(Sender: TObject); var mysqlcon: TMySQL; // MySQL-connection structure presults: pmysql_res; // Pointer to a results structure prow: pmysql_row; // Pointer to a row structure pfields: PMYSQL_FIELDS; // Pointer to a fields array i, j: Integer; // Counters begin // Connect to the server mysql_connect(@mysqlcon, 'localhost', 'root', ''); if mysqlcon.net.last_errno <> 0 then begin ShowMessage (Trim(mysqlcon.net.last_error)); exit; end; // Open the mysql database if mysql_select_db(@mysqlcon, 'mysql') <> 0 then begin mysql_close(@mysqlcon); // Disconnect ShowMessage('Couldn''t open mysql database'); exit; end; presults:= nil; try // Send the query to the server and get the results mysql_query(@mysqlcon, 'SELECT * FROM user'); presults := mysql_store_result(@mysqlcon); // Set the size of the grid StringGrid1.ColCount := presults^.field_count; StringGrid1.RowCount := presults^.row_count + 1; // Fill the grid header with the fields' names pfields := presults^.fields; for j := 0 to presults^.field_count -1 do StringGrid1.Cells[j, 0] := pfields^[j].name; // Fill the grid for i := 1 to presults^.row_count do begin prow := mysql_fetch_row(presults); for j := 0 to presults^.field_count -1 do StringGrid1.Cells[j, i]:= prow^[j]; end; finally mysql_free_result(presults); // Release memory mysql_close(@mysqlcon); // Disconnect end; end; As you can see, it's quite complicated, and this constitutes the main (and I would say only, but very important) disadvantage of using the libmysql.dll library. The advantages are that you have full control, that it's faster than using ODBC, and that it doesn't requiere the BDE. It would be nice to have a TDataset descendant that encapsulates the libmysql.dll API... WINZEOS ------- These components exist, allowing us to access a MySQL server using standard data controls without using BDE/ADO + ODBC. You can find them here: http://www.zeos.dn.ua The package is distributed under the terms of the GNU General Public License, but as we explained you can use it freely for "internal use", including the development of tailor-made applications. ________________________________________________________________________ 3. "POST-IT." SIZABLE WINDOWS WITHOUT BORDER OR TITLE Copyright (c) 2000 Alirio Gavidia <alirio@gavidia.org> To see more of my articles visit: Programación Orientada en Delphi (site in Spanish) http://www.gavidia.org/pod/ Translated to the English language by Ernesto De Spirito with the author's permission. WHY A BORDERLESS AND TITLELESS FORM? ==================================== Four are the fundamental facts in the present essay: The first of them is the existence of programs that mimic Post-it (those little sticky pages that come in notebooks and flood offices with flashy colors). Second, the use of certain undocumented Windows function to drag forms. Third, the problem of how to create an application where the main form is not visible. And fourth, using the Windows task bar. The programs that mimic Post-it I take as reference are mainly TurboNote in Windows and the one of KDE in Linux. Both programs are easily acquirable and do more than the one I present here. However, I consider this a good teaching example. It comes to my mind another program that presents itself without title: the round (analog) clock that comes with Power Toys for Windows. It will be left for a future article. LET'S GET STARTED ================= The obvious is to imitate a post-it note in some way. The first thought is a form with a title bar without the usual buttons (minimize, maximize, etc.) and completely with a plain color. This alternative is possible and requires a bit specialized Windows management. In particular I have chosen a more economic alternative regarding code (or at least that's what I think); and this is eliminating the title bar and form borders (like you would do in a "splash-screen") and place a panel and a memo in a form, the first aligned to top and the second to the client area. MANAGING A FORM WITHOUT BORDERS OR TITLE BAR ============================================ The form with just a panel and a memo will respond without problems to keyboard actions, but it is obvious it won't respond to mouse drags and size changes with the mouse (without borders from where to hold it). The drag is resolved with an undocumented action, at least that's how it was some time ago, thru the message SysCommand. The line shown here, executed from a form, places it in drag state. Perform(wm_SysCommand, $f012, 0) The matter with the messages doesn't get limited to this. The resize modes are also defined that way. For this purpose we defined a set of constants with the appropriate values starting from $f012. sc_DragMove = $f012; sc_Leftsize = $f001; sc_Rightsize = $f002; sc_Upsize = $f003; sc_UpLeftsize = $f004; sc_UpRightsize = $f005; sc_Dnsize = $f006; sc_DnLeftsize = $f007; sc_DnRightsize = $f008; NOTE: If you wonder where these values came from, well, what can I say... I got to know the first one by a Marco Cantú book called "Delphi Developers' Handbook", the rest came out from trial and error. Let me tell you that $f040 produces a disastrous result. Also $f020 and $f030 minimize and maximize respectively, which is not necessary for our application. I don't know if any of this works outside Windows 98. Additionally, in the MouseDown event of the panel and the memo, where we send the messages, it is necessary to call ReleaseCapture before sending the indicated messages. I won't extend much with the code. It's easier to analyze it from Delphi than from an HTML page or a DOC. But notice that it has to be distinguished where a click happened in the panel to know if it is required to resize or just drag the form. Something similar happens with the memo for the resize of the bottom and lateral sides. procedure TfrmNota.Panel1MouseDown( Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer); begin ReleaseCapture; if y<2 then begin if x<4 then Perform(wm_SysCommand, sc_UpLeftsize, 0) else if x>(Panel1.ClientWidth-4) then Perform(wm_SysCommand, sc_UpRightsize, 0) else Perform(wm_SysCommand, sc_UpSize, 0) end else Perform(wm_SysCommand, sc_DragMove, 0) end; sources are part of this article and you will be able to see the note working in detail. In the attached example, apart from the mouse event handling we make use of the Windows Registry to store information relative to the note itself (like its position, font type and color). I presume that if you understand what we have done up to this point, you don't need explanations about the use of the Windows Registry (anyway, its use seems to be well documented in the Delphi Help, and there are examples and information about it in the Internet). AN INVISIBLE MAIN FORM ====================== When I made this program I hadn't though of a really silly problem. The user shall be able to create and destroy notes, but he can't destroy the main form because this finishes the application. Well, then simply with not showing the main form it should suffice. If you want to understand this silly problem create an application in which apart from the main there exists a secondary form; then make the application start showing only the secondary form. My attempts resulted in failure. Now I know this gets accomplished with Application.ShowMainForm := False; in the main program before creating the forms, but back then I didn't know it and I took advantage of the problem to give it an original solution... IT'S NOT A BUG, IT'S A FEATURE ============================== Thinking around the matter, the solution was converting the main form in a splash screen that lasts a certain amount of time and then hides. This code gets executed in a timer: procedure TfrmMain.Timer1Timer(Sender: TObject); begin SaveNotes(Sender); if not oculto then // if not hidden begin oculto := True; ShowWindow(Handle, SW_HIDE); ShowWindow(Application.Handle, SW_HIDE); SetWindowLong( Application.Handle, GWL_EXSTYLE, GetWindowLong(Application.Handle, GWL_EXSTYLE) or WS_EX_TOOLWINDOW and not WS_EX_APPWINDOW); ShowWindow(Application.Handle, SW_SHOW); end end; With this, the main form gets hidden (the next line right after the assignment of the "oculto" (hidden) variable, that by the way is False), and also the presence of the application in the task bar. The rest of the code is relatively simple and contains some routines to save and restore the content and configuration of the notes (the first to disk and the second to the Registry). I believe it doesn't deserve a deep discussion and therefore I leave to the reader the interpretation of the routine. The project as such contains five forms: * note, is the note with the panel and the memo. * GenConfig, is the configuration form of the application, currently only configures formats and counter of the clock. * Config, note configuration (color, alignment and fonts) * Main, is the main form, apart from this it works as a splash screen. * Acerca (About), program version. As a separate comment, note that due to the presence of a Timer it is possible to force an "auto save" for the text in the notes. This is achieved going thru all the forms of type note and saving their contents from the memo. The routine named SaveNotes is executed from the timer (having the precaution of not saving what hasn't changed). Each note has the public variable Changed that is modified when saved and in the OnChange event of the memo. POP-UP MENU =========== The application doesn't have a main menu because it doesn't have a main form. All actions different than interaction with the memo field and mouse movements are done by pop-up menus. There are two: one in the note and one in the icon of the task bar (next to the clock). For this one we used the RX. Therefore at least for this version you will need to have sources. If you don't know them, them you should do it, they are free ("freeware") and very good. RX Library Web Site: http://www.rxlib.com Authors: Fedor Kozhevnikov (fkozh@iname.com) Igor Pavluk (igorp@mail.com) Serge Korolev (korolev@usa.net) -------------------------- The source code that accompanies this article can be downloaded from: http://www.latiumsoftware.com/download/h-notes.zip NOTE: The comments and many names are in Spanish. Sorry... ________________________________________________________________________ 4. LINKS * VCL Components - Searchable collection of more than 4000 Delphi and C++ Builder freeware and shareware components http://vclcomponents.com/ * The Delphi Search Engine - The Delphi search engine indexes components, documents, tips, tricks and any Delphi resource in the web. A Directory of delphi sites is also available. http://www.delphiseek.com/ * delphi3000 - A knowledge platform for Delphi developers including articles, code-snippets, forum, components, tips, tricks, DLL, TreeView, XML, ADO, Internet, Web, GUI... http://www.delphi3000.com/ ________________________________________________________________________ YOU CAN HELP US We need your help to keep this newsletter going and growing. 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Its use implies the acceptance of our licensing terms and disclaimer of warranty you can read at http://www.latiumsoftware.com/en/legal.php where you will also find a note about legal trademarks. Articles are copyright of their respective authors and they are reproduced here with their permission. You can redistribute this newsletter as long as you do it in full (including copyright notices), without changes, and gratis. ________________________________________________________________________ Main page: http://www.latiumsoftware.com/en/pascal/delphi-newsletter.php Group home page: http://groups.yahoo.com/group/pascal-newsletter/ Subscribe/join: pascal-newsletter-subscribe@yahoogroups.com Unsubscribe/leave: pascal-newsletter-unsubscribe@yahoogroups.com Problems with your subscription? eds2004 @ latiumsoftware.com ________________________________________________________________________ Latium Software http://www.latiumsoftware.com/en/index.php Copyright (c) 2000 by Ernesto De Spirito. 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